1. Technical Field of the Invention
The present invention relates generally to the field of image recording apparatus and, more specifically, to an improved method and apparatus by which toner particles are removed from an imaging member.
2. Background Art
The cross-referenced application discloses a method and apparatus for producing images on an imaging member. Such apparatus utilizes a moving imaging member onto which a substantially uniform layer of thermoplastic toner particles is deposited. The toner particles are imagewise heated by a scanning, intensity-modulated laser beam which lightly tacks the heated toner particles to the imaging member. Those toner particles which are not tacked to the imaging member (i.e. the nonheated toner particles) are removed from the imaging member by an electrically biased magnetic brush utilizing magnetic carrier particles. The remaining toner defines an image on the imaging member.
The toner-removing magnetic brush includes a nonmagnetic shell having a magnetic core disposed therein. The core is composed of a series of magnetic strips of alternating polarity. Relative movement is provided between the shell and core, and an electrical bias is applied to the shell. Magnetic carrier particles are applied to the shell and remain there due to their attraction to the magnetic core. When the imaging member is contacted by the carrier particles, the nonheated toner particles are attracted to the carrier particles and are thereby removed from the imaging member.
In the above imaging process, it will be appreciated that a large quantity of toner particles must be removed from the imaging member in a short period of time in order to efficiently create images. In fact, more toner is sometimes removed from the imaging member than is left behind to form the image. To prevent the toner-removing magnetic brush from quickly loading-up with toner particles and thereby rendering the brush ineffective as a toner removing device, a biased roller (referred to as a "detoning" roller) can be arranged to contact the brush "nap" downstream of the nip between the brush and imaging member. Such a roller is electrically biased to strip toner from the carrier particles and thereby allow the denuded carrier particles to be used again to remove toner from the imaging member. The toner on the detone roller is removed by, for example, a skive and is either recycled or discarded. While such a toner removing system can operate effectively at slow speeds, it does not lend itself to high speed imaging. This is because such large amounts of toner particles become attached to the carrier particles that it is very difficult for the detoning roller to remove all the toner from the carrier when images are being created at high speed.